Multi-track sound system for narrow-width motion picture film

ABSTRACT

Narrow-width motion picture systems are provided with a multiple-track sound capability by providing the film with a plurality of magnetic recording stripes and by providing projecting equipment with specially devised adapters for playing back sound tracks recorded on these stripes. The adapters are designed to be compatible with existing equipment, and they include a switching arrangement for permitting the sound tracks to be replayed separately or in combination.

United States Patent 1191 Swerdlow et al.

MULTl-TRACK SOUND SYSTEM FOR NARROW-WIDTH MOTION PICTURE FILM Inventors:Robert Swerdlow, Toronto, Ontario; Emil Schilder, Kensington, Ontario,both of Canada Assignee: Cinacor, Ltd., Ontario, Canada Filed: Mar. 31,1971 Appl. No.: 129,935

US. Cl. 352/27, 179/1002 MP Int. Cl. G03!) 31/02 Field of Search 352/26,27, 28, 29, 30, 37; 179/1002 MP References Cited UNITED STATES PATENTS4/1931 Kuchenmeister 352/37 UX 12/1934 Hanna 352/30 X 8/1949 Rossmann etal... 352/37 2/1952 Camras [79/1002 2/1953 Blaney 352/27 X Mar. 5, 1 9742,676,023 4/1954' lSOm 352 27 ux 2,695,545 ll/l954 Evans 2,826,] 123/1958 Mueller 3,017,466 1 1962 Kerr 3,452,16l 6/1969 I- I afler3,537,781 1 1970 Lemelson 352 27 x Primary Examiner--Joseph F. Peters,Jr. Assistant Examiner-Michael L. Gellner Attorney, Agent, orFirm-Pennie & Edmonds [57] ABSTRACT Narrow-width motion picture systemsare provided with a multiple-track sound capability by providing thefilm with a plurality of magnetic recording stripes and by providingprojecting equipment with specially devised adapters for playing backsound tracks re corded on these stripes. The adapters are designed to becompatible with existing equipment, and they include a switchingarrangement for permitting the sound tracks to be replayed separately orin combination.

3 Claims, 8 Drawing Figures PATENTEUNAR 51w 3.795.440

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FIG. 1B

L Prior Art J INVENTORS ROBERT SWERDLOW EMIL SCHILDER ATTORNEY SPAIENTEDHAR 51w 3.195.440

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ATTORNEYS INVENTORS ROBERT SWERDLOW EMIL SCHILDER PATENTED 5 sum 3 or 4I N VEN TORS ROBERT SWERDLOW EMIL SCHI LDER B MM ATTORNEYS PATENTED 5 74SHEET '8 BF 4 FIG; 6

Pickhp Heads Ourpur SWS 1 med 5 PSA r 6 .M G U G E Photocell ToMicrophone a Amplifiers INVENTORS ROBERT SWERDLOW EMIL SCHILDER flw W W5% ATTORNEYS MULTI-TRACK SOUND SYSTEM FOR NARROW-WIDTH MOTION PICTUREFILM I BACKGROUND OF THE INVENTION The present invention relates to amultiple-track sound recording and reproducing system for use withnarrow-width motion picture film.

Users of narrow-width motion picture equipment have long desired amultiple-track sound capability. The'provision of such a capabilitywould produce substantial advantages to the educational institutions,semi-professionals and amateurs who generally use such equipment. Forexample, educational institutions (which are generally limited to 8 mmor 16 mm equipment by economic necessity), have long sought motionpicture films which have different sound tracks for student audiences ofdifferent grade levels. In addition-- particularly in urban areas-theyhave sought films having different sound tracks in different languagesfor their students who are not yet proficient in English. Moreover,semi-professional and amateur moviemakers have long been desirous ofobtaining a multitrack capability so that they can 'use one track fordialogue while making movies and additional tracks for subsequentlyadding background music or even sound effects.

In addition, the provision of a multiple-track sound capability cansignificantly reduce the amount of film required. One multi-track filmcan replace several single-track films, reducing the film cost and thecost of storage in film libraries.

While multi-track systems are available to professionals, they have notbeen generally available to amateurs and semi-professionals. Forexample, U. S. Pat. No. 2,628,288 issued to D. L. Blaney on Feb. 10,1953, discloses a two-track system using one optical recording track andone magnetic track. This system is useful for the professional but ofonly limited value to the amateur who generally does not have thecomplex equipment required for optical recording. See U. S. Pat. No.2,479,868, issued to P. F. Rossman et al., Aug. 23, 1949.)

Films having two magnetic stripes are commercially available, but it hasnot been considered possible to record an independent sound track on thesecond stripe. Instead, the stripe has b e e n rnerely used for balance.(See SMPTE Standard PH 22, 101-4963.) In U. S. Pat. No. 2,452,16l'issuedto D. I-Iaffler on June 24, 1969, it was suggested that the secondstripe'could be used in conjunction with the first stripe to record astereophonic track; but even in this patent the supposed incapacity ofthe second stripe to record an-independent track was noted; and it wasused only to record the difference signal of the stereophonic track.

SUMMARY OF THE INVENTION Contrary to prior expectations, it has beenfound that narrow-width motion picture film can include a plurality ofmagnetic recording stripes, each capable of recording an independentsound track. In accordance with the invention, narrow-width motionpicture systems are provided with a multiple-track sound capability byproviding the film with a plurality of magnetic recording stripes and byproviding projecting equipment with specially devised adapters forplaying back these tracks. The adapters are designed to be compatiblewith existing equipment. The sound tracks can be replayed separately orsimultaneously.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages, the nature of thepresent invention, and its various features will appear more fully uponconsideration of the various illustrative embodiments now to bedescribed in detail in connection with the accompanying drawings.

In the drawings:

FIGS. 1A and 1B illustrate multi-track narrow-width motion picture filmin accordance with one aspect of the invention;

FIG. 2 illustrates the sound station of a typical prior art motionpicture projector;

FIG. 3 illustrates an adapter for a typical motion picture projector topermit the playback of multi-track, narrow-width film;

FIG. 4 illustrates a first alternative embodiment of such an adapter;

FIG. 5 illustrates a second alternative embodiment;

FIG. 6 is a circuit diagram of a system for controlling the operation ofthe playback systems shown in FIGS. 3-5; and

FIG. 7 illustrates a recording head for recording sound tracks onthefilm of FIGS. 1A and 18.

For convenience of reference, the same numbers are used to denotecorresponding elements throughout the drawings. 1

DETAILED DESCRIPTION Referring to the drawings, FIGS. IA and 1B showfront and cross-sectional views, respectively, of a multitrack,narrow-width motion picture film in accordance with one aspect of theinvention. The film shown in FIG. IA comprises a strip of conventional,narrowwidth motion picture film 10 such as 16mm or super- '8mm filmincluding sprocket holes 11, an optical track 12, and a plurality ofmagnetic tracks 13, each capable of recording an independent soundtrack. As can be' seen by reference to FIG. llB, three tracks are shownin this illustrative embodiment (the stripe adjacent optical track 12comprising two separate tracks). It is clear, however, that up to sixtracks can be provided by putting three additional tracks on theunderside of the film. Preferably, a double magnetic track is placed onor adjacent the conventional optical track in the manner disclosed inthe above-mentioned patent to Blaney. The remaining track is disposed onthe opposing edge of the film.

The magnetic tracks comprise stripes of pulverized magnetic materialsuch as iron oxide powder deposited or coated on the film in accordancewith techniques well known in the art. Each track is approximatelyonesixteenth inch wide. Stripes of this width are sufficient to recordan independent sound track, and they can be predisposed on the edges offilm away, from the exposed or exposable portion.

The film in a conventional projector for sound movies is fed from a reelpast the visual projecting system with an intermittent movement, andthereafter it passes to a sound station where it travels with a uniformmovement, the sound being normally picked up from an optical sound trackalong one edge of the film.

FIG. 2 illustrates a typical conventional mechanism for obtaininguniform movement of the film, subsequent to its visual projection. Themechanism consists rected through the correct path to emerge of a bottomloop sprocket 20, which is driven,"and over which the film 21 passes toa sound drum 22 having a flywheel (not shown), the film being presseddown wardly by a spring loaded snubber idler 23. The film has an opticalsound track adjacent one edge, and light from an exciter lamp 24 isdirected through a lens 25 onto the optical track to cause soundreproduction in the conventional way. .The sounds being reproducedbottom loop sprocket and out of the projector to a takeup reel (notshown)- The projector is often pro-' vided with guide plates 28 whichmake it possible to insert a film by simply pushing its leading edgeinto the projector, the guide plates ensuring that the film is ditakeupreel.

In accordance with a second aspect of the invention,

at the an especially designed adapter is provided for permitting theplayback of the additional magnetic tracks. In particular, the adapteris designed to be interposed between the conventional sound drum and thetakeup reel so that it can be added to most conventional projectors.

FIG. 3 illustrates such an adapter comprising, in essence, a magneticpickup, an auxiliary sound drum and a suitable arrangement of idlers.More specifically, the adapter comprises a spring loaded idler 30 forreceiving film from the conventional sound drum, and a magnetic pickup31 including a plurality of separate pickup heads. These heads should beconstructed of a material which is sufficiently durable to withstandcontact with motion picture film (which is substantially harder thanconventional magnetic tape). The material should not be so soft that thefilm will wear it down, and it should not be so hard that it will cutthrough the film.

A second idler 32 and a subsequent sound drum 33 are positioned to pressthe film against the heads of pickup 31 with each sound track in contactwith a different head. I

A third idler 34 is positioned for receiving film from the sound drumand feeding it to the snubber idler of the conventional sound station atthe same angle it would have come directly from the conventional sounddrum.

In operation, after the film leaves the conventional sound drum 22, itpasses downwardly (following the unbroken arrows) past spring loadedidler 30 (which keeps it in tension), around idler 32 and over magneticpickup 31. For a film having three magnetic sound tracks, the pickup hasthree heads. The idler 32 and subsequent sound drum 33 press the filmagainst these heads, with each sound track in contact with a differentinvention in which the magnetic pickup is disposed between the sounddrum of the conventional sound station and an adapter sound drum.Specifically, this adapter comprises a magnetic pickup 31 and a sounddrum 33 positioned with respect to the sound drum of the conventionalsound station to press the film against the pickup. An additional idler40, which is optional, may be provided between sound drum 33 and theconventional snubber idler in order to provide additional protectionagainst snaking of the film. However, this additional idler isunnecessary if drum 33 is disposed to feed film to the snubber idler atapproximately the same angle as it would arrive from the sound drum ofthe conventional sound station. I V

The components of the adapter can all be mounted on a single casting(not shown) that can be inserted as a unit into the conventionalprojector. The adapter can be provided with guide plates 41 to ensurethat a film can be inserted by pushing its leading edge through theprojector and the guide plates to guide it through the adapter.Additional means (not shown) can be provided to shift one or more guideplates to cause the film as it is inserted to bypass the adapter andfollow the conventional path when the adapter is not required. Thisfeature preventsiunnecessary wear on the magnetic pickup heads when theyare not in use.

As indicated by the broken outline in FIG. 4, the

magnetic pickup can be located at the opposite side of the film ifmagnetic tracks are provided on thebase side of the film. Or, ifdesired, both sides of the film can be provided with up to threemagnetic tracks, and the adapter can be provided with a magnetic pickupfor each track, thus providing for a total of six magnetic tracks. 7

As previously mentioned, the conventional optical sound pickup occurs ata frame which is 26 frames ahead of the frame being visually projected.Similarly, the magnetic pickup heads and the sound recording on themagnetic tracks of the film must bear a known relationship to thepictures on the film, and a convenient standard is that the magneticpickup occurs 32 frames ahead of the frame being visually projected.

FIG. 5 shows an additional and preferred embodiment of the invention inwhich the magnetic pickup is fixedly disposed adjacent an auxiliarydrum. The drum is located in the film path between the sound drum of theconventional sound station and the subsequent snubber idler. Theadvantage of this embodiment'is that it provides the desired adaptationwith a minimum of new components.

In particular, this adapter comprises a magnetic pickup "31 including aplurality of separate pickup heads fixedly disposed-adjacent anauxiliary'rotatable drum 42 by one or more mounting clamps 43 engaging amounting tube 44. The heads of the magnetic pickup are convenientlydisposed on either side of drum 42 to magnetically engage magnetictracks on both edges of film passing around the drum. The drum, in turn,is positioned to feed film passing therearound to the conventionalsnubber idler 26 at any angle suitable for subsequent feeding intoconventional idler 27.

As is the case for the other embodiments, this adapter can be mounted ona single casting that can be inserted as a unit into a conventionalprojector. Suitable guide plates 45 are provided, and guide plate shift-I ventional sound system including an optical pickup,

such as a photocell 50, a pre-amplifier A and an amplifier A Inaddition, a plurality of magnetic pickup heads 51-53 are connected byleads 54-56, respectively, and a switch arm S to amplifiers A and A Theoutput of amplifier A in turn, is connected to amplifier A in theconventional sound system of the projector through switch S An equalizer57 is provided in parallel with A and a pre-set screw adjustment 58 isdisposed between A and A to equalize the volumes between the optical andmagnetic tracks. With this arrangement, one can use a magnetic track,the optical track, or a desired combination of any of these tracks.

FIG. 7 is a schematic illustration of a recording head useful inrecording sound tracks on the multi-track film of FIGS. 1A and 1B. Thehead differs from conventional recording heads primarily in that itincludes a plurality of magnetic recording coils 60, 61, and 62positioned to record on each of the magnetic tracks 13 of film 10. Thecoils 60, 61, and 62 are independently controllable and are preferablyconnected by separate leads 63, 64, and 65, respectively, to a trackselecting switch 66. The switch, in turn, can be connected to a suitableinput microphone and amplifier arrangement.

While the invention has been described in connection with specificembodiments, it is understood that these embodiments are merelyillustrative of the many possible specific embodiments which canrepresent applications of the principles of the invention. Numerous andvaried other arrangements can be devised in accordance with theprinciples of the invention without departing from the spirit and scopeof the invention.

We claim:

1. A sound reproduction system for a narrow-width motion picture systemcomprising:

narrow-width picture film including a plurality of magnetic tracks eachcapable of recording an independent sound track;

a motion picture film projector capable of sound projection forreceiving said narrow-width film, said projector including a soundreproduction system of the type including a driven loop sprocket, asound drum and idler means for pressing film onto said sound drum as itpasses from said sprocket around said sound drum and back towards saidsprocket; and

an adapter for said projector for permitting the playback of soundtracks recorded on said magnetic tracks, said adapter comprising amagnetic pick-up including a plurality of separate pickup heads disposedin a position adjacent the return film path between said sound drum andsaid loop-sprocket, first idler means for tensioning said film-springmeans for spring biasing said idler, second idler means for guiding saidfilm, drum means for maintaining said film in alignment with saidmagnetic pickup head, said second idler means and said drum meanscooperating together to press said film against said magnetic pickuphead, a third idler means for directing said film back along the pathdefined by said sound drum and switching means for switching the soundsystem of said projector among the separate pickup heads of saidmagnetic pickup. 2. A system according to claim 1 wherein saidnarrow-width motion picture film includes an optical sound track.

3. A system according to claim 1 wherein said plurality of magnetictracks comprises at least three magnetic tracks.

1. A sound reproduction system for a narrow-width motion picture systemcomprising: narrow-width picture film including a plurality of magnetictracks each capable of recording an independent sound track; a motionpicture film projector capable of sound projection for receiving saidnarrow-width film, said projector including a sound reproduction systemof the type including a driven loop sprocket, a sound drum and idlermeans for pressing film onto said sound drum as it passes from saidsprocket around said sound drum and back towards said sprocket; and anadapter for said projector for permitting the playback of sound tracksrecorded on said magnetic tracks, said adapter comprising a magneticpick-up including a plurality of separate pickup heads disposed in aposition adjacent the return film path between said sound drum and saidloop sprocket, first idler means for tensioning said film, spring meansfor spring biasing said idler, second idler means for guiding said film,drum means for maintaining said film in alignment with said magneticpickup head, said second idler means and said drum means cooperatingtogether to press said film against said magnetic pickup head, a thirdidler means for directing said film back along the path defined by saidsound drum and switching means for switching the sound system of saidprojector among the separate pickup heads of said magnetic pickup.
 2. Asystem according to claim 1 wherein said narrow-width motion picturefilm includes an optical sound track.
 3. A system according to claim 1wherein said plurality of magnetic tracks comprises at least threemagnetic tracks.